Drill bit



NQVO 11 9 G.- H. GILMAN- DRILL BIT Filed April 2.

1919 2 Sheets-Sheet 1 NW. N, 1924. 1,515,43

ca. H. GILMAN .DRILL BIT Filed April 2, 1919 2 Sheets-Sheet 2 clear, and exact specification.

unit are GEORGE E. GILMAN, or ,oriaamuon'r, new HAMPSHIRE, nssrenon 'ro SULLIVAN 'MAoHINEnY oomranv, a CORPORATION or .MASSACHUSETTS.

ears

DRILL BIT.

Application filed April 2, 1919. Serial no. 287,029.

To all whom, it may concern:

Be it known that I, GFDRGE H. QmMAN, a citizen of the United States, residing at Claremont, in the county of Sullivan and State of New Hampshire, have invented certain new and useful Improvements sin Drill Bits, of which the following is a full,

My invention relates to drill bits and especially to those adapted for use in drilling stone or the like.

It has for its object to provide an improved fast cutting bit having materially increased stamina whereby a hole may be drilled with. the minimum number of changes of drill bits and with the removal shown several embodiments which my inrention may assume in practice, formed on hollow or solid round drill rods, although,

as is obvious, these embodiments may be formed on any other kind ofdrill rod such,

for example, as the hexagonal rods common- Fi 5 is a perspective view showin anot er manner of forming my improved drill bit on a hollow drill steel.

Fig. 6 is an end view of one form of my improved bit on a common form of dril steel.

Fig. 7 is a side elevation thereof.

Figs. 8 and 10 are end views and Figs. 9

and 11 are side elevations thereof recas to separate the different pairs.

tively, showing further modifications in which my bit may be embodied.

Figs. '12 and 13 are an end view" and a side elevation respectively, showing the details of the drill bit illustrated in Fig. 5.

Fig. let is a further modification of the form of bit shown in F ig. 11. I

In these illustrative constructions, I have shown some of the difi'erent embodiments which my invention may assume, as applied to a drill rod 1 which, in some cases, is shown solid, and other cases, as having a longitudinal, axial passageway therein for conducting pressure fiuid'or cleansing fluid to the cutting edge of the bit. These differ.- ent forms'ofmy improved bit are produced on one end of the drill steel, by upsettin this end in a plurality of pairs of radia wings 2, 2 and 3, 3 preferably diametrically disposed with reference to the axis of the bit. Each pair of wings supports, prefer ably, but a single cutting edge, the pair of wings 2 carrying at their extremities the cutting edge 4 and the pair of wings 3 carrying at their extremities, the cutting edge 5. These cutting edges 4; and 5 may assume different forms but in my preferred form, they are are shaped and symmetrically disposed with reference to the axis of the bit. In the embodiments of m invention shown herein, there is a central y disposed, preferably diamond shaped portion 7, which bridges'the gap between the are; shaped cutting edges and carries preferably in alignment with the centers of the are shaped cutting edges 4 and 5, a cutting edge 8,

herein shown as a straight cutting edge equally disposed on opposite sides of the c axis of thebit.

To provide proper clearance for the removal of the cuttings, the bit is preferably provided with longitudinally extending grooves 10. and 11, the grooves 10 being formed between the elements of each pair of wings, and the grooves 11 being so formed form of my, invention as disclosed in the drawings, the grooves 10 and 11 are preferably ,formed of the same depth with the result that the outer supporting wall of the cutting edges adjacentthe centers thereof is. narrower than the supporting section of the bit adjacent the ends of the cutting edges. If desired, the cutting edges 4 and 5 may be given a greater curvature at their center In the I points or the grooves may bemade shallower to obviate this narrowing of the slip- V porting section of the hit. As shown, the

wings are preferably formed of a lower conical section adjacent the drill steel 1 and a reaming edge supporting section 13 disposed 1 preferably at a smaller angle than the conistruction provides an eficient, well supported reaming edge which does not rifle the hole, which gives great eficiency and has a long life. T he reaming edge supporting section 13 merges into the conical section of the wings in a curved line as shown at it and this reaming edge supporting section bounded by the reaming edges 12 and the line 14 may he made as long or as short as is desirable for the particular work for which the drill bit is to be used.

If desired, this form of drill bit may be formed on the end of a hollow drill steel having an axial aperture 15 which may open adjacent the bit in a hole 16 formed to one side of the radialcuttingedge 8 or if desired, it may pass centrally through the cutting edge 8 as shown in Fig. 5'. ln the form shown in Figs. 3 and 4 wherein the pressure 1 fluid is forced out to one side of the radial cutting edge 8, the pressure fluid will act unevenly on the cuttings in the bottom of the hole, but this form gives a greater length of cutting edge and prevents thefor'mation of a cone of rock centrally in the bottom of the drilled hole. If the axial aperture '15 opens directly through the cutting edge 8 as shown in Fig. 5, the pressure fiuid acts equally in all directions from the center of the hole and the small cone of rock which at 21 and the reaming edge v22 which is supwill be formed in the bottom of the hole will be easily broken away by the radial sections of'the "cutting edge 8 which radiate from the opposite sides of the opening 17.

ln'Figs. 6 and Z, I have illustrated my improved bit as applied to the ordinary form of drill steel wherein the entire edge supporting section is formed as a cone, the ends of the cutting edges 4. and 5 terminating in a circle 18 which circle illustrates the size of the hole this drill bit will cut when it is first operated. As is apparent, the cutting edges 4t and 5 terminate in reaming points 19 which will rifle the hole and will rapidly wear away until the size of the hole cut is materially reduced as is shown at 20. This results in a reaming surface formed on the sides of the wings as shown by dotted lines posed to ream the hole and prevent rifling, will not function as a reaming edge at all.

Theseadefects, l have overcome in the present invention by forming the reaming edges 22 in the surface of a cylinder as shown at 12 in the remaining figures. "lhese reaming edges 12 may be supported in a variety of ways, some of which are illustrated in Figs. 8 to it inclusive.

in Fig. 9; the reaming edge sup-porting section 23 is formed cylindrical for a depth suflicient to support the entire reaming edge and as shown in this figure, this depth extends from the point where the cutting edges 4. and 5 merge into the reaming edges to the outer ends of the reaming edges. J. rom this latter point, the cylindrical section is supported by a conical section of the bit which terminates at its other end in the drill steel 1. This reaming edge supporting section 23 provides a veryefiicient means for supporting the reaming edges and will ive these reaming edges a very long life. ilowever, as these reaming edges are worn away, the rock which surrounds the drill hole, then, will come in contact with the outer surface of the cylindrical portion 23 and the reaming will be done to a greater extent as the hole is advancedby reaming surfaces than by the reaming edges. This will result in the rapid wear of the steel and rapid lessening of the gauge of the hole and will necessitate a more frequent change of steels than when the reaming edges 12 do the work of reaming the hole.

As illustrated in Figs. 10, 11, and 14, the cylindrical section 23 may be flattened or otherwise ground 03 centrally of each wing,

and this flattened portion may, if desired,

extend clear to the point of juncture of the reaming edges with the cutting edges as illustrated in Fig. 1( or it may terminate slightly in the rear ofuthis juncture as illustrated at 25 in Fig. 1a. this means, the greater portion of the surface of the cylindrical portion which would become a reaming surface as the bit wears, is removed and the reaming will be done by. the reaming edges for a longer-period, thus increasing the life of the bit and preventing a rapid narrowing of the gauge. of the hole. I

In the preferred form of my invention, as illustrated in 5, 12, and 13, this reaming edge supporting section is preferably formed so that at no time is the reaming done by a reaming surface and so that the reaming edge, as the latter wears, is always maintained substantially in the circumference of a circle.- As is best shown in Fig. 13, the surface 15 of this reaming edge supporting section is preferably formed by a generating line 26 which may be considered as starting at the. juncture of the reaming edges with one of the cutting edges, as 5, this element being preferably disposed at an angle to the axis of the bit, and the surface being generated by moving this element newest illustrated in this figure, this angle is chosen as 5 instead of 7 as shown in Fig. 11,- although, as is apparent, any angle may be posite the mid-portion thereof, and a transverse "cutting edge extending between the most proximate points of said arcuate cutting edges, each of said cutting edges being formed ,at the intersection of inclined chosen and the angle may be varied in acsurfaces which serve'to move the chips and cordance with the character of the materiaL dust toward their'eliev'ed portions of the bit.

to be drilled. If any, two axial planes cut- .ting the bit as at X and Y (Fig. 12) be taken, these planes will cut elements from the supporting section 13 which will deviate from the axis of the bit at 5, or if reference is taken to the cylinder. in which the reaming edges lie, these axial planes will cut elements from the surface 13 and from the surface of the cylinder, which elements are disposed at an angle of 5 to each other. By this preferred construction, it will be seen that I have provided a reaming'edge supporting section whichpat notime and under no conditions of wear, will become a reaming surface, that the reaming edge is equally supported throughout its length, and that the reaming edges will always be maintained in substantially a true circle so that the hole drilled will not be rifled, will not be narrowed rapidly, and will be round.

It will thus be noted that I have provided an improved fastcutting drill bit which may be formed on solid or hollow steels of any type, that the drill bit thus formed will not rifle a hole, will not wear rapidly, and that the cuts made at the bottom of the hole will not be radial cuts only, but also diagonal cuts, and that this form of cutting edge will form chips of substantially a uniform size.

lVhile l have in this application specifically described several embodiments which myinvention may assume in practice, it is to be understood that these forms of the same are used for illustrative purposes only and that the invention may be modified and embodied in various other forms without departing from its spirit or the scope of the appended claims.

What I claim as new and desire to secure by'Letters Patent is:

1. A drill bit having a plurality of sub stantially arcuate cutting edges curving away from the axis ofthe bit, the peripheral surface of said bitbeing longitudinally relieved between the ends of said arcuate edges and also opposite the mid-portions thereof, and a transverse cutting edge normal to one of said cutting edges, each of said edges being formed at "the intersection of inclinedsurfaces which serve to move the chips and dust toward the relieve-d portions of the bit.

2. A drill bit having a plurality ofoppositely disposed substantially arcuate cutting, edges curving away from the axis of.

the bit, the peripheral surface of said bit being longitudinally relieved between the ends of said arcuate edges and also 0p the relieved portions of the hit, an juneans including awn-aperture in the bit tmpermit a flow of liquid from the interior thereof to said cutting edges.

4. A drill bit having a plurality of substantially arcuate cutting edges curving away from the axis of thebit, the peripheral surface of said bit being longitudinally relieved between the ends of said arcuate edges and also' opposite the mid-pqrtions thereof, and a diametrically disposed cutting edge extending between points in said arcuate cut ting edges, each of said edges being formed at the intersection of inclined surfaces which serve to move the chips and the dust toward the relieved portions of the bit, and means comprising an aperture disposed centrally of said diametrically disposed edge for permitting flow from the interior of'the bit to said cutting edges.

5. A rock drill bit comprising a cutting edge'terminating at its ends ina cylindrical surface coaxial with the longitudinal axis of the bit, said cutting edge being formed at the intersection of inclined surfaces so disposed that the traces of said surfaces at any point along the cutting edge upon a plane parallel to the axis of the bit and perpendicularto the cutting edge at that point will lie on opposite sides of a line parallel to the bit axis and passing through the apex of the angle made by said traces,

said surfaces terminating at their ends in lines lying substantially wholly in the cylindrical surface and forming reaming edges, and the peripheral surface of said bit receding from all points along said reaming edges at a slight angle from said cylindrical surface.

6. A drill bit comprising at least one cutting edge terminating at the ends thereof in a cylindrical surface, said cutting edge being formed at the intersection of inclined surfaces terminating at their ends in the periphery of the bit, the end portions of the wedge shaped wing extremities lying between said inclined surfaces being of a and the axis of the bit. a

vmeasured by said cylindrical surface.

til a...

curvature whose trace on a plane perpendicular to the longitudinal axis of the bit is flatter at any point therealong than the arc of. a circle of a radius equal to the-distance between the central point of said trace '4'. A drill bit comprising at least one cutting edge termindting at the ends thereof in a cylindrical surface, said cutting edge .being formed at the intersection of inclined surfaces terminating at their-ends in the periphery of the bit, the end portions of the wedge shaped wing lying between said inclined surfaces being between its ends flatter at any point than an arc of a circle corresponding to the gage of the bit as 8. it rock drill bit comprising a cone shaped head .portion on one end'of a steel of steel, anda reaming edge supporting section of said bar whose surface recedes from the surface of the c linder at the same angle for all points on he reaming edge.-

10. A rock drillbit comprising a cutting edge on one end of a bar of steel and term-- nating in reamingedges disposed in the surface of a cylinder coaxial with the bar of steel, a reaming edge supporting section of saidbar whose surface recedes from the surface of the cylinder at the same angle for all points on the reaming edge, and" a conical shaped section of said bar support"? ing said first named section. c '1 11. A drill bit having a plurality of arcuate cutting edges, reaming edges in which said cutting edges terminate, said reaming edges being disposed in the wall ofa cylinder, and a reaming edge supporting means whose outer surface recedes from the bit comprising a cutting- W nt wall of the cylinder at the same angle at every point on the reaming edge.

12. A rock drill bit comprising a cutting edge-formed on one end thereof, said cut ting edge terminating at the intersection of reaming edges disposed in the surface of a cylinder coaxial with the bit, and supporting means for said reaming edges whose surface recedes from the surface of the cylinder.

13. A drill bit having a cutting edge on oneend thereof, said cutting edge terminating at its opposite ends at the intersection of reaming edges disposed in the surface of a cylinder coaxial With the bit, and supporting means for said reaming edges so formed that transverse planes perpendicula-r to the axis of the bit and cutting said reaming edges will cut the supporting means along curved lines, the distance from the bit axis of every point in which between the reaming edges is less than, the radius of the cylindrical surfaces in which the reaming edges-lie.

. 14. A drill bit having at its end cutting means including a cutting edge portion ter- -minating at at least two angularly spaced points in the surface of a cylinder equal in diameter to the gage of the bit, supporting portions for said cutting edge portion terminating in inclined surfaces at Whose intersection said cutting edge is formed, and reaming edges lying wholly in said cylindrical surface and formed at the extremities of, said supporting portions most remote from the axis of the bit, the surfaces of the supporting portions intermediate said reaming edges being nearer the axis than said cylindrical surface whereby such portions of said surfaces do notcontact with the wall ofa hole reamed by said reaming edges, and whereby as the gage of the bit is diminished as wear occurs the area of contact between said surfaces and the wall of the hole only gradually approaches the full area of said surfaces.

In testimony whereof ll affix my signature.

n. GILMAN. 

